Redline is simply the max engineered safe rpm value for your engine, you can run at or below that value in a lower gear all day if you like. Max torque and HP is developed just shy of redline! Good Luck!

Also max fuel consumption is obtained there as well . . .

Only if the engine already has a fault.

The Red Line is number the manufacturer says it's safe to rev to. Modern cars have the computer reduce power if you try and go past the value anyway.

If the engine was damaged, it had a pre-existing problem.

Yes

sure it blows the engine